Since my proposal is lengthy, I have compiled a document on Google Docs.
While airdrops can instantly distribute tokens to a vast number of people, most of the token recipients do not have a vested interest in the network and thus no incentive to hold or use the tokens. I suggest that airdropped tokens should be locked in a smart contract, which can only be unlocked by active participation in the Free TON network.
One suggested way to unlock the tokens is to use them in Schelling Point Voting for bounty (or contest) submissions. This also provides a fair and decentralized way to check the validity of such submissions. While full prevention of Sybil attacks can only be achieved through KYC procedures, this airdrop model provides strong disincentivizes against both automated and manual Sybil attacks.
The full document can be viewed here: https://docs.google.com/document/d/1EgwYNIPQwLWBtITjvcAbYG_xx4SalK4q-edAmwkh4HA/edit?usp=sharing